This invention relates to an iontophoretic bioelectrode system capable of absorbing an aqueous ionic solution for subsequent iontophoretic delivery into the skin or tissue of a patient.
Iontophoretic bioelectrodes, used in place of hypodermic needles to inject medications into a person's skin or tissue, typically include a pouch or similar enclosure formed with a wettable barrier or a microporous membrane on one side thereof See, for example, U.S. Pat. Nos. 4,250,878, 4,419,092 and 4,477,971. A medication solution containing ions to be delivered into the person's skin or tissue is injected into the pouch by means of a hypodermic needle, a syringe, etc. When the wettable barrier or membrane is placed against a person's skin and an electric current is supplied to the solution, the ions are caused to migrate from the solution, through the wettable barrier or membrane, and into the skin.
For the bioelectrodes described, barriers or membranes are required to retain the solution in the pouch while allowing ions to migrate therethrough. However, such barriers or membranes also inhibit wetting of the skin and thus the migration of ions to a certain extent, as compared to the situation if the solution were in direct contact with the skin.
Also, because of the use of a pouch or similar enclosure to contain the medication solution, a mechanism or structure on the enclosure is necessary for allowing the injection thereinto of the solution. Such structure has typically included some type of orifice containing a plug into which a hypodermic needle or syringe tube may be inserted to allow delivery of the solution through the orifice into the interior of the enclosure, while preventing the outflow of the solution after it has been injected into the enclosure. The requirement for such solution receiving mechanism on the enclosure, of course, increases the cost of the bioelectrode and gives rise to potential leakage locations.